JPS633192B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention is a continuously adjustable conical belt wheel type belt wrap transmission device, which has a tension member circulating between a pair of conical belt wheels. , each pair of conical belt pulleys has a conical belt pulley which is axially movable by means of a hydraulic crimping device in the form of a cylinder-piston unit, in which case the cylinders of the cylinder-piston unit are preferably connected to the conical belt. The pressure piston is axially supported on the shaft of the conical belt wheel pair, and the pressure medium is distributed to the cylinder via a control valve in dependence on the load and the transmission ratio. Concerning things that are shaped like this.

Prior Art This type of belt-wrap transmission device, in which the pressure force between a conical belt pulley and a transmission member circulating therebetween is generated by hydraulic pressure, has been disclosed in numerous patents by the applicant. It is publicly known. In this case, the crimping devices are often arranged in pressure chambers located diagonally opposite one another, so that the wedge shape of the conical belt pulley during operation is symmetrical. However, other arrangements for crimping devices are also known instead of this type.

Problem to be Solved by the Invention This hydraulically controlled transmission has the major disadvantage that the transmission stops functioning when the oil pressure drops, for example due to a leak in the pressure oil circuit or a malfunction of the pressure oil pump. This is particularly disadvantageous when such transmissions are used in motor vehicles.

Therefore, it is an object of the present invention to improve the above-mentioned conical belt wheel type belt-wrapping transmission device equipped with a hydraulic crimping device and a control device so that it can be used even when the hydraulic system fails and the transmission force is small. The purpose of this is to enable the transmission to function, that is, to allow the car to travel at a more leisurely speed. Furthermore, in order to use the transmission in a motor vehicle, the construction of the transmission must be compact.

Means for Solving the Problem In order to solve this problem, the configuration of the present invention includes:
In conical belt wheel type belt-wrapped transmissions of the type mentioned at the outset, the axial support of the pressure piston on the shaft of the conical belt wheel is achieved via a mechanical cam-type crimping device, which cam-type crimping device It consists of a plurality of axially projecting transmission projections provided on the boss of the pressure piston and an equal number of cams cooperating with the transmission projections, the cams being axially supported on the shaft. The cam holder is provided on the end face of a cam holder that is non-rotatably connected to the shaft, and in this case, each cam consists of two cam surfaces that are substantially symmetrical in the circumferential direction, and the symmetry of each cam is two cam surfaces, each consisting of a steep inner section transitioning to a common cam bottom and a relatively flat outer section following said section, so that during normal hydraulic function the pressure The transmission protrusion of the piston is located at the bottom of the cam, whereas in the event of a hydraulic failure, the relative position between the cam and the transmission protrusion changes, creating an axial pressing force, and in this case, the outer side of the cam surface The angle in the section is set small so that the axial crimping force occurring in the event of a hydraulic failure ensures a non-slip force transmission in the tension member.

Effect When configured as in the present invention, a simple mechanical cam-type crimping device is provided on the conical belt pulley unit on the driven side, and this cam-type crimping device is activated when the hydraulic system is functioning. does not produce a crimping effect, i.e. the transmission projection of the pressure piston is located without play on the cam bottom between the cam ramp sections and serves only for the torque transmission between the conical belt sheave and the shaft; If the hydraulic system malfunctions and the oil pressure drops,
The transmission projection of the pressure piston reaches from the cam base to a relatively flat outer section of the cam surface, where the axial forces generated during torque transmission (axial clamping force) directly pass from the pressure piston to the conical belt pulley. , which presses the movable conical belt pulley on the driven side towards the front, ie moves the transmission at a low speed to produce a sufficient crimping effect in this position. As a result, emergency operation for the motor vehicle can be guaranteed even in the event of a complete drop in oil pressure. At the same time, this cam-type crimping device also plays an auxiliary role during start-up if the pump pressure does not build up quickly enough.

Although the use of a combined mechanical and hydraulic crimping device is known, for example from German Patent Application No. 2744947,
However, in this case the mechanical crimping device is designed to work simultaneously in parallel with the hydraulic crimping device, i.e. the conical belt pulley combines the mechanically and hydraulically generated forces. It is now being loaded with the same force. In contrast to this known transmission, in the transmission according to the invention the mechanical cam-type crimping device is located on the axial support of the pressure piston and is therefore not active during normal hydraulic operation. Only when the oil pressure falls below a predetermined minimum value can the pressure piston be moved towards the movable conical belt pulley by means of a cam crimping device, and the transmission be adjusted in the direction of "low speed". .

Embodiment In a preferred embodiment of the invention, the transmission projection has a rotatably mounted roller at its free end. With this configuration, relative movement between the cam and the transmission protrusion can be performed more smoothly in the event of a hydraulic failure.

In order to also enable a displacement of the pressure piston in the axial direction, a further embodiment of the invention provides that the pressure piston is mounted on a boss of a conical belt pulley assigned to the pressure piston so that the pressure piston can be moved axially but not rotatably. It is located in

According to a further embodiment, the pressure piston is loaded against a movable conical belt pulley by means of a pressure spring, in which case the transmission cannot be adequately supplied with oil. Even during no-load operation, the movement is adjusted in the "low speed" direction.

Embodiment The conical belt wheel type belt-wrapped transmission shown in FIG. 1 has a drive shaft 1 and a driven shaft 2. A pair of conical belt pulleys 3 and 4 are mounted on the drive shaft 1.
A pair of conical belt pulleys 5, 6 is arranged on the driven shaft 2, and a tension member 7 circulates between the two pairs of conical belt pulleys 3, 4; 5, 6. The conical sheave 6 has an outer cylindrical wall 8 for a pressure piston 10 which is non-rotatably connected to the inner boss 9 of the conical sheave.
The pressure cylinder is constructed as an axially displaceable pressure cylinder with a pressure cylinder, whereby a pressure chamber 11 is formed between the conical belt pulley 6 and the pressure piston 10. This pressure chamber 11 includes a conduit 12, an axial hole 13 and a hole 14 provided in the shaft 2, and a boss 9.
Pressure oil is introduced through holes 15 provided in the tension member 7, thereby creating the necessary clamping force acting on the tension member 7.

The emergency crimping device comprises an axially movable pressure piston 10 which is non-rotatably connected to a conical belt pulley 6.
and a cam holder 19 which is non-rotatably connected to the driven shaft 2, in which case the boss 17 of the pressure piston 10 is provided with a transmission projection 18 on the outside.
is located. While the cam holder 19 was previously supported by the shaft 2 via a retaining ring or the like in the axial direction, the other end surface of the cam holder 19 was provided with a plurality of rings around the entire circumference. Cams 20 are integrally molded and are adapted to cooperate with the transmission projections 18. The plurality of transmission protrusions 18 and cams 20 are distributed over the entire circumference. The symmetrical cam surface of each cam 20 in this case each consists of a steep inner section leading to a common cam base and a relatively flat outer section following this section.

In the operating state under hydraulic load, the transmission protrusion 18 is pressed against the cam bottom of the cam 20 (see the solid line in FIG. 2).
In this position, the cam 20 serves only for the transmission of torque in the manner of a cardan joint, but not for the crimping of the tension member. When the oil pressure drops, press spring 2
1 and, if a torque is generated, an emergency crimping device, the pressure piston 10 is connected to the conical belt pulley 6.
This conical pulley 6 pushes the tension member 7 outwards until the tension member 7 occupies its maximum circulation circle. Correspondingly, the tension member 7 in the drive-side sheave unit occupies its smallest circulation circle. This minimum circulation circle is defined by the mechanically limited maximum expansion of the conical belt pulley. Under the action of a torque, the pressure piston 10, which is not rotatable relative to the conical belt pulley 6 but is movable in the axial direction, and thus the transmission lug 18, is moved relative to the cam holder 19 such that the transmission lug 18, for example, It is additionally moved in the circumferential direction until it occupies the position shown in broken lines in the figure. As a result of the torque and the cam inclination angle 22, the conical sheave 6 is mechanically pressed against the tension member 7. The spring clamping action, which can only carry out a limited torque transmission, is therefore compensated for by a significantly increased torque-related clamping action. If the hydraulic system is installed in reverse, the operations described above proceed in the opposite direction.

A conical belt pulley 6 for sealing the pressure chamber 11
A gasket 37 is arranged between the boss 9 and the pressure piston 10.

The drive side belt pulley unit has a conventional structure. The conical belt pulley 4 together with the sleeve wall 24 forms a pressure cylinder for a shaft-fixed pressure piston 25 . In FIG. 1, only the collar of the pressure piston 25 located on the drive shaft 1 is shown. Pressure fluid is also fed to the pressure cylinder via a conduit 26 and a shaft hole (not shown).

Conduit 12 and conduit 26 are connected to a control spool valve 27 with four control edges, by means of which pressure oil supplied from pump 28 is transferred to conduit 12 or conduit 26. It is distributed to 26 people. Surplus pressure medium is returned to the pressure medium container via conduit 32 and relief valve 33. The pumped pressure medium is also returned to the pressure medium container from each pulley unit (cylinder-piston unit) via the control spool valve 27 and the return line 34 and, preferably, a preload valve 35 provided. Adjustment of the displacement of the control spool valve 27 with four control edges takes place via a control lever 29 which is pivotally connected to this control spool valve 27. Control lever 29 to maintain the transmission ratio
One end engages in a circumferential groove 30 of an axially movable conical belt pulley 4. Furthermore, the control lever 29 can be adjusted via a hand lever 31 in order to change the transmission ratio at will.

FIG. 3 shows a particularly advantageous design for a mechanical cam-type crimping device. In this embodiment, instead of the transmission lug 18, a rotatably mounted roller 36 is provided.

Effects of the Invention As can be seen from the above description, in the conical belt sheave type belt-wrapped transmission device according to the present invention, the pressure piston of the conical belt sheave unit on the driven side is axially compressed via a mechanical cam type crimping device. Since it is supported on the associated shaft, a torque-related emergency crimping action is guaranteed even in the event of a drop in the oil pressure in the event of a failure of the hydraulic system.

[Brief explanation of the drawing]

Fig. 1 is a schematic diagram showing a hydraulically controlled conical belt car type belt wrapping transmission device equipped with a hydraulic support device and an emergency crimping device on the conical belt car unit on the driven side; FIG. 3, which is a view of the emergency crimping device seen from the direction of the arrow in the figure, shows an emergency crimping device of the type that includes a roller instead of a transmission protrusion. 1... Drive shaft, 2... Driven shaft, 3, 4, 5, 6...
Conical belt pulley, 7...Tension member, 8...Outer cylinder wall, 9
...Boss, 10...Pressure piston, 11...Pressure chamber, 1
2... Conduit, 13... Axial hole, 14, 15... Hole, 1
7...Boss, 18...Transmission protrusion, 19...Cam holder,
20...Cam, 21...Pressure spring, 22...Cam inclination angle, 24...Outer cylinder wall, 25...Pressure piston, 26...
Conduit, 27... Control spool valve, 28... Pump, 2
9... Control lever, 30... Circumferential groove, 31... Hand lever, 32... Conduit, 33... Relief valve, 34... Return conduit, 35... Preload valve, 36... Roller, 37
…rubber seal.

Claims (1)

[Scope of Claims] 1. A continuously adjustable conical belt wheel type belt-wrapping transmission device, comprising a tension member 7 circulating between a pair of conical belt wheels 3, 4; 5, 6; Each pair of conical belt pulleys has a conical belt pulley 4; 6 which is axially movable by means of a hydraulic crimping device in the form of a cylinder-piston unit, in which case the cylinder of the cylinder-piston unit is connected to the conical belt pulley. , whereas the pressure piston 10 is axially supported on the shaft 1; 2 of the conical belt wheel pair, the pressure medium being connected to the cylinder via a control valve 27 in dependence on the load and the transmission ratio. In the form that has come to be distributed in
Pressure piston 1 in the axis 1; 2 of the conical belt wheel
0 axial support is achieved via a mechanical cam-type crimping device, which cam-type crimping device is connected to a plurality of axially projecting transmission lugs 18 on the boss 17 of the pressure piston 10. , an equal number of cams 20 cooperating with the transmission prongs, the cams being axially supported on the shaft 2 and connected to the shaft in a non-rotatable manner. In this case, the cams 20 each consist of two substantially symmetrical cam surfaces in the circumferential direction, and the two symmetrical cam surfaces of each cam 20 transition to a common cam bottom. It consists of a steeply sloped inner section and a relatively flat outer section following this section, in which the transmission lug 18 of the pressure piston 10 is located at the bottom of the cam during normal functioning of the hydraulic pressure. On the other hand, in the case of a hydraulic failure, the relative position of the cam 20 and the transmission protrusion 18 changes, producing an axial pressing force, in which case the angle 22 in the outer section of the cam surface is created in the event of a hydraulic failure. A belt-wrap transmission of the conical belt sheave type, characterized in that the axial pressing force is set small to ensure a non-slip force transmission in the tension member 7. 2. The conical belt wheel type belt-wrap transmission device according to claim 1, wherein the transmission protrusion 18 has a roller 36 rotatably supported at its free end. 3. The pressure piston 10 is mounted axially but non-rotatably on the boss 9 of the movable conical belt pulley 6 assigned to it. The conical belt wheel type belt-wrapped transmission device described above. 4 The pressure piston 10 is activated by the pressure spring 21,
A conical belt sheave type belt wrapping transmission device according to any one of claims 1 to 3, which is loaded toward a movable conical belt sheave 6.